The present invention relates to a safety device for use in conjunction with hypodermic syringes and other similar needle-bearing medical appliances for protecting the users thereof from inadvertent punctures from contaminated needles. More particularly, the present invention relates to several embodiments of an improved needle guard assembly having a slidably movable guard member associated therewith, the guard member being movable between a retracted position wherein the syringe needle is fully exposed during use and an extended position wherein such needle is completely enclosed and encased within the guard member thereby safely housing the contaminated needle therewithin after use. The present assemblies also include a locking mechanism which automatically locks the protective guard member in its fully extended position around the contaminated needle after use thereby preventing further subsequent use of the devices. Although it is anticipated that the various embodiments of the present invention will be used primarily on hypodermic syringes, the present devices are likewise adaptable for use on a wide variety of other needle-bearing medical devices such as I.V. catheter placement units, blood-collecting apparatus and the like.
Contaminated hypodermic needles present a substantial health hazard and can result in transmission of a number of potentially life-threatening diseases such as hepatitis, acquired immune deficiency syndrome (AIDS), gonorrhea and other various diseases. One group which is particularly at risk in dealing with such devices are professional health care workers and housekeeping and janitorial personnel who must handle these skin-puncturing contaminated devices after they have been used. There, therefore, exists a great need to protect such personnel from accidental skin puncture injuries from such contaminated needles as well as a need to provide a safe and efficient means for disposing the same.
In an effort to provide some protection to health care workers and others, a wide variety of devices for shielding and guarding needles after use have been designed and manufactured. Such known devices teach a wide variety of constructions for accomplishing this task. For example, some of the known prior art constructions utilize complicated extension and retraction means for controlling the positioning of the shield or guard member about the used needle as well as complicated locking mechanisms for holding the shield member in place after use. See, for typical examples, the constructions shown in U.S. Pat. Nos. 4,664,654 and 4,752,290. Other known constructions are designed such that the entire exterior portion of the syringe becomes masked by the guard or shielding member when the device is retracted to expose the needle. See, for typical examples, the constructions shown in U.S. Pat. Nos. 4,738,663, 4,391,272 and 4,702,738. Still other examples of needle shielding devices are those shown and described in U.S. Pat. Nos. 3,890,971, 4,737,144 and 4,631,057. All such prior art devices suffer from certain disadvantages and shortcomings including being overly complex, expensive and difficult to manufacture, cumbersome to handle and install, hard to manipulate during operation, and many of such devices require manual retraction and/or extension of the guard or shield member before and after use. For these reasons, many of the prior art devices have proven to be ineffective and commercially unacceptable. In addition, none of the known needle shielding devices are as simple structurally as the present construction and none utilize as efficient and effective means for both retracting and extending the guard member during use and automatically locking the guard member in its fully extended position around the contaminated needle after use. For these and other reasons, most known needle shielding devices have enjoyed limited usefulness.